Semiconductor device, power converting device, driving device, vehicle, and elevator

ABSTRACT

A semiconductor device of an embodiment includes a first diode having a first anode and a first cathode, the first anode connected to either one of first and second electrodes of a first transistor having the first and second electrodes and a first gate electrode; a first electric resistor having a first one end connected to the first cathode and a first other end connected to positive pole of a direct-current power source; a first capacitor having a second one end and a second other end connected to the first cathode; a second capacitor having a third one end connected to negative pole of the direct-current power source and a third other end connected to the second one end of the first capacitor; and a second switching element connected in parallel to the second capacitor.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2017-124199, filed on Jun. 26, 2017, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor device,a power converting device, a driving device, a vehicle, and an elevator.

BACKGROUND

With a power transistor that performs high-speed switching operation, asurge voltage may be generated due to a parasitic inductance when thepower transistor is turned off. The generation of the surge voltage isdisadvantageous, since the surge voltage may cause breakdown of a gateinsulating film and/or ringing in a circuit. Since the surge voltage ishigh and is generated for a short time period, detection of the surgevoltage is difficult.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a semiconductor device according to afirst embodiment;

FIG. 2 is a circuit diagram of a power converting device according tothe first embodiment;

FIG. 3 is a view showing one example of a waveform of a surge voltage;

FIG. 4 is a view showing characteristics of surge voltage detection ofthe semiconductor device according to the first embodiment;

FIG. 5 is a circuit diagram of a semiconductor device according to amodification of the first embodiment;

FIG. 6 is a circuit diagram of a power converting device according to asecond embodiment;

FIG. 7 is a circuit diagram of a semiconductor device according to thesecond embodiment;

FIG. 8 is a circuit diagram of a semiconductor device according to athird embodiment;

FIG. 9 is a circuit diagram of a semiconductor device according to afourth embodiment;

FIG. 10 is a circuit diagram of a semiconductor device according to afifth embodiment;

FIG. 11 is a schematic diagram of a driving device according to a sixthembodiment;

FIG. 12 is a schematic diagram of a vehicle according to a seventhembodiment;

FIG. 13 is a schematic diagram of a vehicle according to an eighthembodiment; and

FIG. 14 is a schematic diagram of an elevator according to a ninthembodiment.

DETAILED DESCRIPTION

A semiconductor device according to an embodiment of the presentdisclosure includes: a first diode having a first anode and a firstcathode, the first anode being electrically connected to either one of afirst electrode and a second electrode of a first transistor having thefirst electrode, the second electrode, and a first gate electrode; afirst electric resistor or a first switching element having a first oneend and a first other end, the first one end being electricallyconnected to the first cathode, the first other end being electricallyconnected to a positive pole of a direct-current power source having thepositive pole and a negative pole; a first capacitor having a second oneend and a second other end, the second other end being electricallyconnected to the first cathode; a second capacitor having a third oneend and a third other end, the third one end being electricallyconnected to the negative pole, the third other end being electricallyconnected to the second one end of the first capacitor; and a secondswitching element electrically connected between the third one end andthe third other end of the second capacitor in parallel to the secondcapacitor.

Embodiments of the present disclosure will be described below withreference to the drawings. Note that, in the following description,identical or similar members and the like are given identical referencenumbers, and a description of the members and the like having beendescribed once is omitted as appropriate.

The “semiconductor device” herein is a concept encompassing anintegrated circuit (IC) including a plurality of elements formed in asingle chip, an electronic circuit board on which a plurality ofelectronic parts are disposed, or a power module made by a combinationof a plurality of elements such as discrete semiconductors.

First Embodiment

A semiconductor device according to the present embodiment includes: afirst diode having a first anode and a first cathode, the first anodebeing electrically connected to either one of a first electrode and asecond electrode of a first transistor having the first electrode, thesecond electrode, and a first gate electrode; a first electric resistoror a first switching element having a first one end and a first otherend, the first one end being electrically connected to the firstcathode, the first other end being electrically connected to a positivepole of a direct-current power source having the positive pole and anegative pole; a first capacitor having a second one end and a secondother end, the second other end being electrically connected to thefirst cathode; a second capacitor having a third one end and a thirdother end, the third one end being electrically connected to thenegative pole, the third other end being electrically connected to thesecond one end of the first capacitor; and a second switching elementelectrically connected between the third one end and the third other endof the second capacitor in parallel to the second capacitor.

A power converting device according to the present embodiment includes:a first transistor having a first electrode, a second electrode, and afirst gate electrode; a first diode having a first anode and a firstcathode, the first anode being electrically connected to either one ofthe first electrode and the second electrode; a first electric resistoror a first switching element having a first one end and a first otherend, the first one end being electrically connected to the firstcathode, the first other end being electrically connected to a positivepole of a direct-current power source having the positive pole and anegative pole; a first capacitor having a second one end and a secondother end, the second other end being electrically connected to thefirst cathode; a second capacitor having a third one end and a thirdother end, the third one end being electrically connected to thenegative pole, the third other end being electrically connected to thesecond one end of the first capacitor; and a second switching elementelectrically connected between the third one end and the third other endof the second capacitor in parallel to the second capacitor.

FIG. 1 is a circuit diagram of a semiconductor device according to thepresent embodiment. The semiconductor device according to the presentembodiment is a surge-voltage detection circuit 110.

FIG. 2 is a circuit diagram of a power converting device according tothe present embodiment. The power converting device according to thepresent embodiment is an inverter circuit 210 including thesurge-voltage detection circuits 110.

FIG. 1 shows a part of the inverter circuit 210. FIG. 1 shows details ofa configuration of one of the surge-voltage detection circuits 110.

The inverter circuit 210 shown in FIG. 2 includes three sets of low-sidetransistors 10 (first transistors) and high-side transistors 20, thethree surge-voltage detection circuits 110, a positive terminal P, anegative terminal N, an output terminal U, an output terminal V, anoutput terminal W, and detection terminals D′. The positive terminal Pis connected to a positive pole 30 a of a direct-current power source30, and the negative terminal N is connected to a negative pole 30 b ofthe direct-current power source 30. For example, a smoothing capacitor40 is provided between the positive terminal P and the negative terminalN in parallel to the direct-current power source 30. The invertercircuit 210 is a three-phase inverter. Each of the detection terminalsD′ outputs a surge-voltage detection result from a respective one of thesurge-voltage detection circuits 110.

A voltage of the direct-current power source 30 is, for example, 200 Vor more and 1500 V or less.

Each of the low-side transistors 10 and the high-side transistors 20 is,for example, an insulated gate bipolar transistor (IGBT). To thelow-side transistors 10 and the high-side transistors 20, freewheeldiodes (not illustrated) are connected, for example.

Each of the surge-voltage detection circuits 110 is, for example, an ICincluding a plurality of elements formed in a single chip or anelectronic circuit board on which a plurality of electronic parts aredisposed. Each of the surge-voltage detection circuit 110 detects asurge voltage generated between a respective one of the low-sidetransistors 10 and a respective one of the high-side transistors 20.

FIG. 1 shows, from among the three sets of low-side transistors 10 andhigh-side transistors 20 in the inverter circuit 210, one set oflow-side transistor 10 and high-side transistor 20 that are connected tothe output terminal U. FIG. 1 also shows one of the surge-voltagedetection circuits 110 connected to the one set of low-side transistor10 and high-side transistor 20.

The surge-voltage detection circuit 110 includes a diode 111 (firstdiode), an electric resistor 112 (first electric resistor), a capacitor113 (first capacitor), a capacitor 114 (second capacitor), a switchingelement 115 (second switching element), a sample-and-hold circuit 116, aswitching element 117, an input terminal A, an input terminal B, aninput terminal I, and a detection terminal D.

The low-side transistor 10 of the inverter circuit 210 has an emitterelectrode 10 a (first electrode), a collector electrode 10 b (secondelectrode), and a gate electrode 10 c (first gate electrode). Thehigh-side transistor 20 of the inverter circuit 210 has an emitterelectrode 20 a, a collector electrode 20 b, and a gate electrode 20 c.

The input terminal A of the surge-voltage detection circuit 110 iselectrically connected to the positive pole 30 a of the direct-currentpower source 30. The input terminal B of the surge-voltage detectioncircuit 110 is electrically connected to the negative pole 30 b of thedirect-current power source 30.

The input terminal I of the surge-voltage detection circuit 110 iselectrically connected to the collector electrode 10 b of the low-sidetransistor 10 and to the emitter electrode 20 a of the high-sidetransistor 20. The input terminal I is electrically connected to aposition in the electric circuit where a surge voltage may be generated.

The detection terminal D of the surge-voltage detection circuit 110outputs a surge-voltage detection result.

The diode 111 has an anode 111 a (first anode) and a cathode 111 b(first cathode). The input terminal I is electrically connected to theanode 111 a. The anode 111 a is electrically connected to the collectorelectrode 10 b of the low-side transistor 10 and to the emitterelectrode 20 a of the high-side transistor 20.

The electric resistor 112 has an end 112 a (first one end) and an end112 b (first other end). The end 112 a is electrically connected to thecathode 111 b of the diode 111. The end 112 b is electrically connectedto the positive pole 30 a of the direct-current power source 30 via theinput terminal A. The electric resistor 112 has a function to reset avoltage increase at position Y caused by a surge voltage.

The capacitor 113 has an end 113 a (second one end) and an end 113 b(second other end). The end 113 b is electrically connected to thecathode 111 b of the diode 111.

The capacitor 114 has an end 114 a (third one end) and an end 114 b(third other end). The end 114 a is electrically connected to thenegative pole 30 b of the direct-current power source 30 via the inputterminal B. The end 114 b is electrically connected to the end 113 a ofthe capacitor 113.

A capacitance of the capacitor 114 is greater than a capacitance of thecapacitor 113, for example. The capacitance of the capacitor 114 is tentimes or more the capacitance of the capacitor 113, for example.

The switching element 115 is electrically connected between the end 114a and the end 114 b of the capacitor 114 in parallel to the capacitor114. The switching element 115 is, for example, a transistor. Theswitching element 115 has a function to reset a voltage (at position Zin FIG. 1) between the capacitors 113 and 114 to a potential at thenegative pole 30 b of the direct-current power source 30.

The sample-and-hold circuit 116 includes an operational amplifier 116 a,a diode 116 b, and a capacitor 116 c. The sample-and-hold circuit 116has a function to maintain, for a predetermined time period, a peakvalue of a voltage inputted to the operational amplifier 116 a. Aconfiguration of the sample-and-hold circuit 116 is not limited to theconfiguration shown in FIG. 1, as long as the sample-and-hold circuit116 has a function to maintain the peak value for a predetermined timeperiod.

The switching element 117 is electrically connected parallel to thecapacitor 116 c. The switching element 117 is, for example, atransistor. The switching element 117 has a function to reset a voltageat an output side of the sample-and-hold circuit 116 to a potential atthe negative pole 30 b of the direct-current power source 30.

Turning on/off of the switching elements 115 and 117 is controlled by,for example, a switching controller 50. The switching controller 50 is,for example, a microcomputer. The switching controller 50 is providedoutside the surge-voltage detection circuit 110, for example.

Next, operation and effects of the semiconductor device and the powerconverting device according to the present embodiment will be described.

With a power transistor that performs high-speed switching operation, asurge voltage may be generated due to a parasitic inductance when thepower transistor is turned off. The generation of the surge voltage isdisadvantageous, since the surge voltage may cause breakdown of a gateinsulating film and/or ringing in a circuit.

A peak value of the surge voltage generated against the power transistoris as high as some hundred volts, and a pulse width thereof at the peakis as short as some tens of nanoseconds. Therefore, it is difficult todetect the peak value of the surge voltage only by the existingsample-and-hold circuit 116, whose circuit configuration is shown inFIG. 1.

According to the present embodiment, it is possible to maintain the peakvalue of the surge voltage for a certain time period due torectification action by the diode 111 and to reduce the peak value ofthe surge voltage through capacitive-division by the capacitors 113 and114, so as to detect the peak value of the surge voltage. Thus, it ispossible to provide a surge-voltage detection circuit capable ofdetecting a peak value of a surge voltage generated against a powertransistor, which surge voltage is high and lasts for a short timeperiod. Furthermore, according to the present embodiment, it is possibleto provide a surge-voltage detection circuit having a simpleconfiguration that can be incorporated in a power converting device suchas an inverter circuit. This will be described in detail below.

In a steady state, a voltage at position Y in FIG. 1 is fixed at avoltage of the positive pole 30 a of the direct-current power source 30via the input terminal A. The following will describe, as an example, acase where the voltage of the positive pole 30 a of the direct-currentpower source 30 is 400 V.

In a steady state, a voltage at position Z in FIG. 1, i.e., a positionbetween the capacitors 113 and 114 is reset to a voltage of the negativepole 30 b of the direct-current power source 30. The resetting of thevoltage can be performed by short-circuiting position Z to the negativepole 30 b of the direct-current power source 30 via the switchingelement 115 and the input terminal B. The following will describe, as anexample, a case where the voltage of the negative pole 30 b of thedirect-current power source 30 is 0 V.

FIG. 3 is a view showing one example of a waveform of a surge voltagethat may be generated at position X in FIG. 1. As shown in FIG. 3, apeak value of the surge voltage is, e.g., 100 V, and a pulse widththereof at the peak is, e.g., 20 nanoseconds.

When a surge voltage having a peak value of 100 V is generated atposition X, a voltage at position Y is also increased by 100 V via thediode 111, so that the voltage at position Y becomes 500 V. Even afterthe surge voltage at position X calms down and the voltage at position Xreturns to 400 V, the voltage at position Y is maintained due torectification action of the diode 111 for a certain time period at 500V, to which the value of the surge voltage has been added. This gives atime allowance, thereby making it easier to detect the surge voltage.

The voltage at position Z in FIG. 1 is subjected to capacitive-divisionby the capacitors 113 and 114, so as to be reduced to a voltage lowerthan 500 V. Particularly in a steady state, since the voltage atposition Z is reset to 0 V, the voltage at position Z is a voltageresulting from capacitive-division only on the increased amount (=100 V)due to the surge voltage. Thus, the peak value of the surge voltage tobe detected is reduced. This makes it easier to detect the peak value.Furthermore, a signal-to-noise (S/N) ratio in detection of the surgevoltage is improved.

Due to the voltage at position Y maintained for a certain time period,the voltage at position Z is maintained for a certain time period. Inaddition, by adjusting a capacity ratio between the capacitors 113 and114, it is possible to significantly reduce the voltage at position Zfrom the peak value of the surge voltage. Therefore, it is possible todetect the voltage by the existing sample-and-hold circuit 116. Thevoltage outputted from the sample-and-hold circuit 116 is detected bythe detection terminal D.

FIG. 4 is a view showing characteristics of surge voltage detection ofthe semiconductor device according to the present embodiment. FIG. 4shows a simulation result of a voltage detected by the detectionterminal D when the surge voltage having the waveform shown in FIG. 3 isinputted to position X in FIG. 1. FIG. 4 shows a voltage obtained bycorrecting the detected voltage for the gain of the surge-voltagedetection circuit 110.

As is clear from FIG. 4, it is possible to detect 100 V, which is thepeak value of the surge voltage, by the surge-voltage detection circuit110.

The peak value of the surge voltage detected by the detection terminal Dcan be used to generate an alarm signal, for example. Also, the peakvalue of the surge voltage detected by the detection terminal D can beused to turn off the low-side transistor 10 and the high-side transistor20 of the inverter circuit 210, for example.

After the peak value of the surge voltage is detected, the voltage atposition Y returns to 400 V of the steady state, since the electricresistor 112 is electrically connected to the positive pole 30 a of thedirect-current power source 30. The voltage at position Z is caused toreturn to 0 V by turning on the switching element 115. The voltage atthe detection terminal D is caused to return to 0 V by turning on theswitching element 117.

A parasitic capacitance of the diode 111 is low. This minimizes anincrease of the loss of the inverter circuit 210 caused by provision ofthe surge-voltage detection circuit 110.

In order to adequately reduce the voltage at position Y, a capacitanceof the capacitor 114 is preferably greater than a capacitance of thecapacitor 113. In order to adequately reduce the voltage at position Y,the capacitance of the capacitor 114 is preferably ten times or more thecapacitance of the capacitor 113.

(Modification)

FIG. 5 is a circuit diagram of a semiconductor device according to amodification of the present embodiment. The semiconductor deviceaccording to the modification is a surge-voltage detection circuit 190.The semiconductor device according to the modification includes a metaloxide semiconductor field effect transistor (MOSFET) 118 instead of theelectric resistor 112. In terms of this, the semiconductor deviceaccording to the modification is different from the semiconductor deviceaccording to the embodiment shown in FIG. 1. The MOSFET 118 is oneexample of the first switching element.

The MOSFET 118 has a source electrode 118 a (first one end), a drainelectrode 118 b (first other end), and a gate electrode 118 c.Controlling the voltage applied to the gate electrode 118 c switcheson/off of the MOSFET 118, which functions as a switching element.

Employing the MOSFET 118 as the first switching element enables quickreset operation.

As described above, according to the present embodiment and themodification thereof, it is possible to provide a surge-voltagedetection circuit capable of detecting a peak value of a surge voltagegenerated against a power transistor, which surge voltage is high andlasts for a short time period. Furthermore, it is possible to provide asurge-voltage detection circuit having a simple configuration that canbe incorporated in a power converting device such as an invertercircuit. Moreover, it is possible to provide an inverter circuitincluding a surge-voltage detection circuit capable of detecting a peakvalue of a surge voltage.

Second Embodiment

A power converting device according to the present embodiment furtherincludes: a variable resistor electrically connected to the first gateelectrode of the first transistor; and a controller configured tocontrol a resistance value of the variable resistor based on a voltagevalue of the second one end of the first capacitor. In terms of this,the power converting device according to the present embodiment isdifferent from the power source driving circuit according to the firstembodiment. In the following description, explanations of theoverlapping contents with the first embodiment are omitted.

FIG. 6 is a circuit diagram of a power converting device according tothe present embodiment. The power converting device according to thepresent embodiment is an inverter circuit 220 including surge-voltagedetection circuits 120. FIG. 7 is a view showing a part of the powerconverting device according to the present embodiment.

FIG. 7 is a circuit diagram of a semiconductor device according to thepresent embodiment. FIG. 7 shows details of a configuration of one ofthe surge-voltage detection circuits 120.

The inverter circuit 220 according to the present embodiment providesso-called active gate control, by which a gate voltage of the powertransistor is actively controlled.

The inverter circuit 220 includes variable resistors 60. One of thevariable resistors 60 is electrically connected to a gate electrode 10 c(first gate electrode) of a low-side transistor 10 (first transistor),and another of the variable resistors 60 is electrically connected to agate electrode 20 c of a high-side transistor 20.

The surge-voltage detection circuit 120 includes a sample-and-holdcircuit 116, an analog-to-digital converter 121, and a microcomputer 122(controller).

A voltage value of an end 113 a (second one end) of a capacitor 113(first capacitor), i.e., a voltage value at position Z is inputted tothe microcomputer 122 via the sample-and-hold circuit 116 and theanalog-to-digital converter 121. The voltage value may be a differencebetween a potential value of the position Z and a potential value of aground.

The voltage value at position Z is based on a peak value of a surgevoltage. Based on the peak value of the surge voltage worked out fromthe voltage value at position Z, the microcomputer 122 outputs aninstruction to change resistance values of the variable resistors 60.Consequently, gate charging/discharging currents of the low-sidetransistor 10 and the high-side transistor 20 are changed. Thus, theinverter circuit 220 is controlled so that the surge voltage becomes apredetermined voltage value or less.

There is no limitation on the configuration of the variable resistor 60,as long as a resistance thereof is variable. For example, the variableresistor 60 is a MOSFET that performs analog operation. In response tothe instruction from the microcomputer 122, for example, a gate voltageof the MOSFET changes, and thus a resistance changes. Alternatively, forexample, the variable resistor 60 is a plurality of MOSFETs connected inparallel. By changing the number of MOSFETs that are in an on-state andan off-state, a resistance is changed.

Turning on/off of the switching element 115 is also controlled by aninstruction from the microcomputer 122.

As described above, according to the present embodiment, it is possibleto provide an inverter circuit capable of suppressing a surge voltage byactively controlling a gate voltage of a power transistor with use of asurge-voltage detection circuit.

Third Embodiment

In a semiconductor device according to the present embodiment, thesecond switching element is a second transistor having a thirdelectrode, a fourth electrode, and a second gate electrode, the thirdelectrode being electrically connected to a negative pole, the fourthelectrode being electrically connected to the third other end of thesecond capacitor. In terms of this, the semiconductor device accordingto the present embodiment is different from the first embodiment.Furthermore, the semiconductor device according to the presentembodiment further includes: a third capacitor having fourth one end andfourth other end, the fourth one end being electrically connected to thethird electrode, the fourth other end being electrically connected tothe second gate electrode; a second resistor having fifth one end andfifth other end, the fifth one end being electrically connected to thefourth one end of the third capacitor, the fifth other end beingelectrically connected to the fourth other end of the third capacitor;and a third electric resistor having sixth one end and sixth other end,the sixth one end being electrically connected to the fifth other end ofthe second electric resistor, the sixth other end being electricallyconnected to the first anode. In terms of this, the semiconductor deviceaccording to the present embodiment is different from the firstembodiment. In the following description, explanations of theoverlapping contents with the first embodiment are omitted.

FIG. 8 is a circuit diagram of a semiconductor device according to thepresent embodiment. The semiconductor device according to the presentembodiment is a surge-voltage detection circuit 130.

The surge-voltage detection circuit 130 includes a diode 111 (firstdiode), an electric resistor 112 (first electric resistor), a capacitor113 (first capacitor), a capacitor 114 (second capacitor), a switchingelement 115 (second switching element), a sample-and-hold circuit 116,an input terminal A, an input terminal B, an input terminal I, adetection terminal D, a capacitor 131 (third capacitor), an electricresistor 132 (second electric resistor), and an electric resistor 133(third electric resistor).

The switching element 115 is a MOSFET. The MOSFET has a source electrode115 a (third electrode), a drain electrode 115 b (fourth electrode), anda gate electrode 115 c (second gate electrode). The source electrode 115a is electrically connected to a negative pole 30 b of a direct-currentpower source 30 via the input terminal B. The drain electrode 115 b iselectrically connected to an end 114 b of the capacitor 114.

The capacitor 131 has an end 131 a (fourth one end) and an end 131 b(fourth other end). The end 131 a is electrically connected to thesource electrode 115 a. The end 131 b is electrically connected to thegate electrode 115 c.

The electric resistor 132 has an end 132 a (fifth one end) and an end132 b (fifth other end). The end 132 a is electrically connected to theend 131 a of the capacitor 131. The end 132 b is electrically connectedto the end 131 b of the capacitor 131.

The electric resistor 133 has an end 133 a (sixth one end) and an end133 b (sixth other end). The end 133 a is electrically connected to theend 132 b of the electric resistor 132. The end 133 b is electricallyconnected to an anode 111 a of the diode 111.

When a surge voltage is generated at position X in FIG. 8, the surgevoltage is subjected to resistance division by the electric resistors132 and 133, and a resultant is supplied to the capacitor 131 and thegate electrode 115 c. Following detection of a peak value of the surgevoltage by the detection terminal D, the switching element 115 isautomatically turned on after being delayed for a predetermined timeperiod, so that the voltage at position Z is reset to 0 V. After that,the voltage of the gate electrode 115 c drops, and accordingly theswitching element 115 is automatically turned off.

According to the present embodiment, as well as in the first embodiment,it is possible to provide a surge-voltage detection circuit capable ofdetecting a peak value of a surge voltage generated against a powertransistor, which surge voltage is high and lasts for a short timeperiod. Furthermore, it is possible to provide a surge-voltage detectioncircuit having a simple configuration that can be incorporated in apower converting device such as an inverter circuit. Moreover, thepresent embodiment enables automatic reset of the surge-voltagedetection circuit.

Fourth Embodiment

A semiconductor device according to the present embodiment furtherincludes a fifth capacitor electrically connected between a first anodeand a third electric resistor. In terms of this, the semiconductordevice according to the present embodiment is different from the thirdembodiment. In the following description, explanations of theoverlapping contents with the third embodiment are omitted.

FIG. 9 is a circuit diagram of a semiconductor device according to thepresent embodiment. The semiconductor device according to the presentembodiment is a surge-voltage detection circuit 140.

The surge-voltage detection circuit 140 includes a diode 111 (firstdiode), an electric resistor 112 (first electric resistor), a capacitor113 (first capacitor), a capacitor 114 (second capacitor), a switchingelement 115 (second switching element), a sample-and-hold circuit 116,an input terminal A, an input terminal B, an input terminal I, adetection terminal D, a capacitor 131 (third capacitor), an electricresistor 132 (second electric resistor), an electric resistor 133 (thirdelectric resistor), and a capacitor 141 (fifth capacitor).

The capacitor 141 is electrically connected between an anode 111 a ofthe diode 111 and the electric resistor 133.

As well as the third embodiment, the present embodiment enablesautomatic reset of a surge-voltage detection circuit. Furthermore, sincea direct current component of a surge voltage is interrupted by thecapacitor 141, a loss of a power converting device and the like causedby addition of the surge-voltage detection circuit 140 is reduced in thepresent embodiment, as compared to the third embodiment.

Fifth Embodiment

A semiconductor device according to the present embodiment furtherincludes: a second diode having a second anode and a second cathode, thesecond anode being electrically connected to the fourth other end of thethird capacitor, the second cathode being electrically connected to thefirst anode, the second diode being electrically connected parallel tothe third electric resistor and the fifth capacitor. In terms of this,the semiconductor device according to the present embodiment isdifferent from the fourth embodiment. In the following description,explanations of the overlapping contents with the fourth embodiment areomitted.

FIG. 10 is a circuit diagram of a semiconductor device according to thepresent embodiment. The semiconductor device according to the presentembodiment is a surge-voltage detection circuit 150.

The surge-voltage detection circuit 150 includes a diode 111 (firstdiode), an electric resistor 112 (first electric resistor), a capacitor113 (first capacitor), a capacitor 114 (second capacitor), a switchingelement 115 (second switching element), a sample-and-hold circuit 116,an input terminal A, an input terminal B, an input terminal I, adetection terminal D, a capacitor 131 (third capacitor), an electricresistor 132 (second electric resistor), an electric resistor 133 (thirdelectric resistor), a capacitor 141 (fifth capacitor), and a diode 151(second diode).

The diode 151 has an anode 151 a (second anode) and a cathode 151 b(second cathode). The anode 151 a is electrically connected to an end131 b of the capacitor 131. The cathode 151 b is electrically connectedto an anode 111 a of the diode 111. The diode 151 is provided inelectrically parallel to the electric resistor 133 and the capacitor141.

As well as the fourth embodiment, the present embodiment enablesautomatic reset of a surge-voltage detection circuit. Furthermore, sincethe present embodiment includes the diode 151, the switching element 115turns off more quickly in the present embodiment, as compared to thefourth embodiment.

Sixth Embodiment

A driving device according to the present embodiment is a driving deviceincluding the power converting device according to the first embodiment.

FIG. 11 is a schematic diagram of a driving device according to thepresent embodiment. A driving device 1000 includes a motor 340 and aninverter circuit 210. The motor 340 is driven by an alternating-currentvoltage outputted from the inverter circuit 210.

According to the present embodiment, the characteristics of the drivingdevice 1000 are improved, since the present embodiment includes theinverter circuit 210 capable of detecting a surge voltage.

Seventh Embodiment

A vehicle according to the present embodiment is a vehicle including thepower converting device according to the first embodiment.

FIG. 12 is a schematic diagram of a vehicle according to the presentembodiment. A vehicle 1100 according to the present embodiment is arailway vehicle. The vehicle 1100 includes a motor 340 and an invertercircuit 210.

The motor 340 is driven by an alternating-current voltage outputted fromthe inverter circuit 210. A wheel 90 of the vehicle 1100 is rotated bythe motor 340.

According to the present embodiment, the characteristics of the vehicle1100 are improved, since the present embodiment includes the invertercircuit 210 capable of detecting a surge voltage.

Eighth Embodiment

A vehicle according to the present embodiment is a vehicle including thepower converting device according to the first embodiment.

FIG. 13 is a schematic diagram of a vehicle according to the presentembodiment. A vehicle 1200 according to the present embodiment is anautomobile. The vehicle 1200 includes a motor 340 and an invertercircuit 210.

The motor 340 is driven by an alternating-current voltage outputted fromthe inverter circuit 210. A wheel 90 of the vehicle 1200 is rotated bythe motor 340.

According to the present embodiment, the characteristics of the vehicle1200 are improved, since the present embodiment includes the invertercircuit 210 capable of detecting a surge voltage.

Ninth Embodiment

An elevator according to the present embodiment is an elevator includingthe power converting device according to the first embodiment.

FIG. 14 is a schematic diagram of an elevator (lift) according to thepresent embodiment. An elevator 1300 according to the present embodimentincludes a car 610, a counterweight 612, a wire rope 614, a hoistingmachine 616, a motor 340, and an inverter circuit 210.

The motor 340 is driven by an alternating-current voltage outputted fromthe inverter circuit 210. The hoisting machine 616 is rotated by themotor 340, so that the car 610 moves up and down.

According to the present embodiment, the characteristics of the elevator1300 are improved, since the present embodiment includes the invertercircuit 210 capable of detecting a surge voltage.

The first to fifth embodiments and the modification have dealt with theinverter circuit as an example of the power converting device.Alternatively, however, a DC-DC converter can be employed as the powerconverting device. In addition, the foregoing has explained, as anexample, a case where a surge voltage generated against the transistorof the power converting device is detected by the surge-voltagedetection circuit. Alternatively, however, the surge-voltage detectioncircuits according to the embodiments and the modification can beapplied to detect a surge voltage generated against a transistor used indevices other than the power converting device.

The sixth to ninth embodiments have dealt with, as examples, the caseswhere the semiconductor device and the power converting device accordingto the present disclosure are applied to the driving device, thevehicle, or the elevator. Alternatively, however, the semiconductordevice and the power converting device according to the presentdisclosure can be applied to, for example, a power conditioner of aphotovoltaic power generating system.

While certain embodiments have been described, these embodiments havebeen presented byway of example only, and are not intended to limit thescope of the inventions. Indeed, a semiconductor device, a powerconverting device, a driving device, a vehicle, and an elevatordescribed herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe devices and methods described herein may be made without departingfrom the spirit of the inventions. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the inventions.

What is claimed is:
 1. A semiconductor device comprising: a first diodehaving a first anode and a first cathode, the first anode beingelectrically connected to either one of a first electrode and a secondelectrode of a first transistor having the first electrode, the secondelectrode, and a first gate electrode; a first electric resistor or afirst switching element having a first one end and a first other end,the first one end being electrically connected to the first cathode, thefirst other end being electrically connected to a positive pole of adirect-current power source having the positive pole and a negativepole; a first capacitor having a second one end and a second other end,the second other end being electrically connected to the first cathode;a second capacitor having a third one end and a third other end, thethird one end being electrically connected to the negative pole, thethird other end being electrically connected to the second one end ofthe first capacitor; and a second switching element electricallyconnected between the third one end and the third other end of thesecond capacitor in parallel to the second capacitor.
 2. Thesemiconductor device according to claim 1, further comprising asample-and-hold circuit electrically connected to the second one end ofthe first capacitor.
 3. The semiconductor device according to claim 1,wherein a capacitance of the second capacitor is greater than acapacitance of the first capacitor.
 4. The semiconductor deviceaccording to claim 1, wherein a capacitance of the second capacitor isten times or more a capacitance of the first capacitor.
 5. Thesemiconductor device according to claim 1, wherein the second switchingelement is a second transistor having a third electrode, a fourthelectrode, and a second gate electrode, the third electrode beingelectrically connected to the negative pole, the fourth electrode beingelectrically connected to the third other end of the second capacitor.6. The semiconductor device according to claim 5, further comprising: athird capacitor having a fourth one end and a fourth other end, thefourth one end being electrically connected to the third electrode, thefourth other end being electrically connected to the second gateelectrode; a second resistor having a fifth one end and a fifth otherend, the fifth one end being electrically connected to the fourth oneend of the third capacitor, the fifth other end being electricallyconnected to the fourth other end of the third capacitor; and a thirdelectric resistor having a sixth one end and a sixth other end, thesixth one end being electrically connected to the fifth other end of thesecond electric resistor, the sixth other end being electricallyconnected to the first anode.
 7. The semiconductor device according toclaim 6, further comprising a fifth capacitor being electricallyconnected between the first anode and the third electric resistor. 8.The semiconductor device according to claim 7, further comprising asecond diode having a second anode and a second cathode, the secondanode being electrically connected to the fourth other end of the thirdcapacitor, the second cathode being electrically connected to the firstanode, the second diode being electrically connected parallel to thethird electric resistor and the fifth capacitor.
 9. A power convertingdevice comprising: a first transistor having a first electrode, a secondelectrode, and a first gate electrode; a first diode having a firstanode and a first cathode, the first anode being electrically connectedto either one of the first electrode and the second electrode; a firstelectric resistor or a first switching element having a first one endand a first other end, the first one end being electrically connected tothe first cathode, the first other end being electrically connected to apositive pole of a direct-current power source having the positive poleand a negative pole; a first capacitor having a second one end and asecond other end, the second other end being electrically connected tothe first cathode; a second capacitor having a third one end and a thirdother end, the third one end being electrically connected to thenegative pole, the third other end being electrically connected to thesecond one end of the first capacitor; and a second switching elementelectrically connected between the third one end and the third other endof the second capacitor in parallel to the second capacitor.
 10. Thepower converting device according to claim 9, further comprising: avariable resistor electrically connected to the first gate electrode ofthe first transistor; and a controller configured to control aresistance value of the variable resistor based on a voltage value ofthe second one end of the first capacitor.
 11. The power convertingdevice according to claim 10, further comprising: a sample-and-holdcircuit electrically connected to the second one end of the firstcapacitor, wherein the controller controls the resistance value of thevariable resistor based on a voltage value outputted from thesample-and-hold circuit.
 12. The power converting device according toclaim 9, wherein a capacitance of the second capacitor is greater than acapacitance of the first capacitor.
 13. The power converting deviceaccording to claim 9, wherein a capacitance of the second capacitor isten times or more a capacitance of the first capacitor.
 14. A drivingdevice comprising the power converting device according to claim
 9. 15.A vehicle comprising the power converting device according to claim 9.16. An elevator comprising the power converting device according toclaim 9.